This made me try my own combination reverb in FL studio (I'm guessing there's a way to do this in Ableton). I took my synth and routed it first so that the volume of the output was used as a CV, then used that CV to alternate between two reverb units: one short ambient reverb that is on when a note is being played, and one long reverb that only turns on when the output from the synth falls below the detection threshold. This gave a clean reverb while playing notes, even fast sequences, but then filled in the empty space when the synth was not being played, no automation necessary.

This made me try my own combination reverb in FL studio (I'm guessing there's a way to do this in Ableton). I took my synth and routed it first so that the volume of the output was used as a CV, then used that CV to alternate between two reverb units: one short ambient reverb that is on when a note is being played, and one long reverb that only turns on when the output from the synth falls below the detection threshold. This gave a clean reverb while playing notes, even fast sequences, but then filled in the empty space when the synth was not being played, no automation necessary.

That sounds interesting. I think it can be done in Live with an effect rack and the max4live envelope follower device.
I'll have to try that sometime